Process for continuously treating spunlaced nonwoven polyester textiles on a tenter frame

ABSTRACT

A process for dyeing a spunlaced nonwoven polyester fabric which comprises padding the fabric with an aqueous pad liquor including disperse polyester dye, leveling compound and tackifier and then passing the thus padded fabric through a tenter frame at 350* to 400*F for 20 to 90 seconds whereby the fabric is continuously and simultaneously dyed and heat set.

United States Patent Reid, Jr. et al.

PROCESS FOR CONTINUOUSLY TREATING SPUNLACED NONWOVEN POLYESTER TEXTILES ON A TENTER FRAME Inventors: James P. Reid, Jr.; Bobby L.

McConnell, both of Greensboro, NC.

Burlington Industries, Inc., Greensboro, NC.

Filed: June 13, 1973 Appl. No.: 369,592

Assignee:

US. Cl. 8/18; 8/17; 8/65;

8/66 Int. Cl D06p 5/00 Field of Search 8/18, 17, 65, 66

References Cited UNITED STATES PATENTS 10/1934 Fikentscher 8/18 OTHER PUBLICATIONS Keaton et al., J. Soc. Dyers and Col., June 1964, pages 312 322.

Primary Examiner-Donald Levy Attorney, Agent, or Firm-Cushman, Darby & Cushman [5 7] ABSTRACT A process for dyeing a spunlaced nonwoven polyester fabric which comprises padding the fabric with an aqueous pad liquor including disperse polyester dye, leveling compound and tackifier and then passing the thus padded fabric through a tenter frame at 350 to 400F for 20 to 90 seconds whereby the fabric is continuously and simultaneously dyed and heat set.

7 Claims, No Drawings PROCESS FOR CONTINUOUSLY TREATING SPUNLACED NONWOVEN POLYESTER TEXTILES ON A TENTER FRAME The present invention relates to a process for continuously treating, i.e. dyeing and finishing polyester fabric on a tenter frame. The invention is particularly useful for the processing of nonwoven fabric, especially spunlaced nonwovens.

BACKGROUND OF THE INVENTION Polyester fabric is dyed using various methods and apparatus, e.g. becks, jigs, beams and thermosol units. Normally, it is necessary to carry out the following operations in order to obtain a dyed and finished polyester fabric: prescour (i.e. fabric preparation), dyeing, postscour, drying, finishing, drying and/or curing. It will be appreciated that these numerous operations are time-consuming and it would be desirable to eliminate one or more of the indicated steps provided the quality of the dyed and finished product is not lowered.

The type of equipment to be used for dyeing polyester depends on various factors, e.g. the construction of fabric, the desired hand and appearance. Due to the construction of spunlaced non-Wovens, for example, many of the pieces of equipment noted earlier herein such as becks are not suitable for dyeing this material. Thus, is beck dyeing, the movement of the cloth through the dye liquor and across the reel causes considerable surface distortion and some pull down in width or necking of the fabric. In jig dyeing even more necking is observed due to higher tension on the fabric. Conventional thermosol equipment is also unsatisfactory due to high tension. Furthermore, dyeings obtained are unacceptable in appearance, i.e., they are unlevel and/or spotty. Of the methods available, the most suitable for the spunlaced non-Wovens is beam dyeing where the fabric is wound on large perforated beams, placed in a beam machine and dye liquor is then pumped through the fabric from the inside of the beam to the outside. This eliminates any pull or stretch on the fabric in the wet state and acceptable goods can be produced by this method. However, the method involves a number of steps, extra equipment and considerable labor.

Another disadvantage to beam dyeing is the flattening of the goods. This is undesirable for many fabric styles. Flattening of goods can also result in thermosol dyeing at high temperatures especially if the'fabric contains textured or bulked polyester yarns. For example, 100% textured polyester loses its bulk or texture when heated above a temperature of 350 360F during conventional thermosol dyeing.

OBJECTS OF THE INVENTION It will be appreciated from the above that there is considerable room for improving upon the dyeing and finishing of polyester fabrics, e.g. spunlaced nonwovens or other types thereof. Accordingly, an object of the invention is to provide an improved process for dyeing and finishing polyester fabrics whereby prior art disadvantages are obviated. A more specific object of the invention is to make it possible to eliminate certain prior art operations, e.g. washing after dyeing, while obtaining highly uniform dyeing and otherwise satisfactory results. A further object is to provide a process for continuously and simultaneously dyeing, finishing, heat setting and curing polyester fabrics. Other objects will also be apparent from the following description of the invention.

SUMMARY OF THE INVENTION Briefly stated, the above objects are realized by the provision of a process which comprises padding the polyester fabric, e.g. a spunlaced nonwoven, with an aqueous pad liquor including a polyester dye, a thermosoling agent or leveling compound, a tackifier and preferably a curable resin finishing agent, and then passing the thus padded fabric through a pin tenter frame, heated to about 350 400F and using a dwell time of 2090 seconds, to obtain a dyed, heat set fabric which is also simultaneously resin-finished and cured if a resin finishing agent is included in the pad liquor. With such process, highly effective dyeing and finishing can be obtained and the product can be cut to desired size and shipped or stored without the need for an after-wash or scour for shades up to medium depth.

The fabric may be held in the stretched or relaxed condition, as desired, as it is passed through the tenter frame, the fabric being heat set in the stretched condition or after controlled shrinkage depending on the degree of relaxation, i.e. overfeed.

DETAILED DESCRIPTION OF THE INVENTION As will be evident from the above, the process of the invention involves dyeing and heat setting, and preferably resin finishing, with stretching or relaxing and shrinking a polyester fabric in one operation by a single pass through a pin tenter frame.

The polyester fabric is preferably polyester although blends of polyester with minor amounts of other fibers, e.g. rayon or cotton, :in amounts up to about 20% by weight can be used. The polyester may be textured or non-textured and the fabric may be nonwoven, especially useful results being obtained with spunlaced nonwovens of the type described in U.S. Pat. Nos. 3,434,188; 3,485,706; 3,485,708; 3,485,709; 3,486,168; 3,493,462; 3,494,821; 3,498,874; and 3,508,308. For example, U.S. Pat. No. 3,485,706 discloses a wide variety of textile-like, nonwoven, spunlaced fabrics which are produced by traversing fibrous material with high-energy liquid streams while supported on an apertured member, such as a perforated plate or woven wire screen, to consolidate the material in a repeating pattern of entangled fiber regions and interconnecting fibers. The fibers are randomly entangled in a manner which holds the fibers of the fabric in place without the need of bonding agents. Patentee further illustrates a means for preparing loose layers of f1- bers and treating the layer with liquid jetted at a pressure of at least 200 p.s.i.g. from a row or small orifices to convert the layer directly into coherent highlystable, strong spun-laced, non-woven fabrics which resemble many textile fabrics prepared by conventional process steps such as mechanical spinning and weaving.

The fabric may be padded with pad liquor using any conventional type of padder, e.g. a vertical roll or submerged roll padder. As will be appreciated, the rolls should be uniform across the width so that the pad liquor is padded uniformly and at constant pick-up across the width of the fabric.

Any available form of pin tenter frame, e.g. the Artos type, may be used for present purposes. The tenter frame selected should, however, be one which provides even air flow across the fabric to avoid uneven dyeing,

i.e., face-to-face or side-to-side shading. The tenter frame should also be equipped with overfeed means to allow as much as 30% overfeed, so that the fabric can be relaxed during processing to permit controlled shrinkage. Tenter frames may be composed of successive chambers or zones, e.g. 8-10, provided with separate means for circulating hot air therethrough and it may be desirable in certain circumstances involving the practice of the invention to vary the temperature of the circulating air. It may be particularly useful, for example, to use air at 400F in the first zone with the temperature, reduced to 390F and 380F in the next two zones, respectively, with the hot air in the rest of the zones being at 360370F. In this way, the fabric may be essentially flash dried in the first two or three zones with the dyeing, finishing, heat setting and curing being completed in the subsequent zones.

The pad liquor comprises, in addition to the polyester dye or mixture of dyes, and finishing agent if used, at least two essential components, i.e. leveling compound (or wetting or dispersing agent) and tackifier. Other components, e.g. antifoaming agents such as nonsilicon antifoams, may also be included in the pad liquor for special effects. However, for present purposes, the leveling compound and tackifier must be used to obtain the desired results. The leveling agent should be one which promotes microdispersion of the dye and otherwise improves diffusion of the dye into or around the polyester fibers. Suitable for use as the leveling agent are sodium tridecyl sulfate, ethoxylated alkyl aryl sulfonates, cationic nylon blends (such as Leveling Agent 100) and the like. Particularly preferred is the product known as Levalin TPC (Baychem Inc) which analyzes as follows:

35% water 6% isopropanol 4% benzyl alcohol 22% C -C branched aliphatic sulfate, amine salt 20% alkyl aryl sulfated ethylene oxide adduct, am-

monium salt 10% ethoxylated nonyl phenol 3% iminodipropionitrile Equivalent results are obtainable with the following Formulations A and B:

FORMULATION A 10% polyethoxylated nonyl phenol (nonionic detergent) 33% ammonium salt of alkyl aryl sulfated ethylene oxide adduct (Alipal CO-436, 60% active) 42% sodium tridecyl sulfate (Sipex EST, 52% active) 6% isopropanol 4% benzyl alcohol 3% iminodipropionitrile 2% water FORMULATION B Same as Formulation A but includes only 30% Sipex (73% active) with an additional 12% water.

Levalin TPC and Formulations A and B apparently tend to solubilize the dye but, no matter how they function, it is evident that they promote highly effective dispersion or diffusion of the dye about the polyester fibers and make possible marked advantages over prior procedures. In particular, thermosoling of the dye in the tenter frame can be carried out at lower temperatures (30F lower) than the temperatures normally used with the same dyes in prior procedures and (2) much better use of the dye, i.e. better yield in terms of the depth of color per amount of dye used, is realized (e.g. 30-50% less dye can be used to give equivalent shades).

The tackifier functions to prevent or control migration of the dye during heating in the tenter frame, particularly in the early stages where the fabric is being dried. In prior art procedures thickeners such as sodium alginate, and bean gums, are used to control migration but, for the present process, it is important to use a material which controls dye migration but does not necessarily function as a thickener. Particularly desirable for use herein is an ammonium salt of polyacrylic acid. This salt increases tackiness rather than viscosity of the pad liquor and apparently functions much like a size in effectively attaching itself to, or encapsulating, the polyester fibers, the dye and finish, if used, being thus held in position on the fibers to give the improved results indicated above. Sodium polyacrylate which is solubilized by the addition of ammonia to give an aqueous solution of pH above about 8.4 may also be effectively used as the tackifier component. The tackifier thus functions to prevent dye and finish migration and, because of this, the pad liquor need not include other special antimigration agents such as the alginates or gums. The polyacrylate tackifier used herein becomes an integral part of the ultimate finish after tenter frame processing and does not require an after wash to remove. It also does not cause any problems of lightfastness, washfastness or other related properties, as is often the case with antimigration agents.

' The dye component in the pad liquor can be any conventional and available disperse dye or mixture thereof known to be suitable for dyeing polyesters. Typical of such dyes are the so-called Palanil dyestuffs, the application of which to polyesters is described in brochure by BASF entitled Palanil Dyestuffs on Polyester Fiber". Polyester disperse dyes with hydroxy groups and which can behave like vat dyes, may also be effectively used in the present process. The advantages of the invention, regardless of the polyester disperse dye which is used, are that substantially less dye need be used for equivalent depths of dyeing compared with prior procedures thus reducing dye costs, elimination of the need for an after wash or scour at least in respect of light to medium shades, and the possibility of using lower temperatures (20-30F) than the temperatures normally required for optimum results with the dyes involved. For example, if a disperse dye is normally used at 420F in the thermosol dyeing of polyester fabric, a temperature of about 390-400F can be used in the present process or if the normal thermosoling temperature is 390400F, a temperature of 360370F can be used with the present process.

The finishing agent, if included in the pad liquor, is preferably but not necessarily a film-forming acrylic polymer as conventionally used for finishing textiles. A wide variety of such polymers is available and the polymer selected necessarily depends on the properties desired in the finished product. A soft polymer, for example, an ethyl acrylate/butyl acrylate copolymer may be used to provide hand or the polymer may be selected to give improved pill resistance, a stabilizing effect, shrinkage control, or the like. Typically the resin finishing agent comprises a copolymer of lower alkyl acrylates and/or methacrylates although other types of tex tile finish acrylate polymers may be used, for example, fast-curing acrylic copolymers as described in U.S. Pat. No. 3,446,777 or self-cross-linking acrylic polymers as disclosed in U.S. Pat. No. 3,157,562, the disclosures of these patents being incorporated herein by reference. The various Rhoplex textile acrylics, e.g. Rhoplex HA16, K-3 (available from Rohm and Haas Company), etc. may be used herein. Other finishing additives, for example, thermosetting resins such as epoxies or ureaor melamine-formaldehyde precondensates, softeners such as polyethylene, and/or antistatic agents, may also be used. The essential feature is that the finishing agent or agents are included in the pad liquor with the dye, leveling agent and tackifier and are cured on the textile while dyeing and heat setting on the tenter frame. If an acid catalyst is necessary for curing the finishing agent, however, care should be taken (for example, by using a buffer) to avoid any undesirable effect on the other pad liquor components, particularly the tackifier. In other words, the pad liquor components should be so chosen as to be compatible.

As an illustration, the pad liquor, which should have a pH of at least 7, may have the following composition, on a percent by weight basis:

(1) dyestuff 001% (2) leveling .253% (based on dyestuff weight agent and preferably in equal parts up to 2% maximum) (3) tackifier 05-15%, preferably 08-10% (4) finishing up to 15%, usually from 13%, but agent depends on agent used and its purpose (5) water balance Optionally the composition may also include a defoamer (0. l-0.5%), preferably a nonsilicone foamer.

The pickup of pad liquor in the padding operation will vary depending on the nature of the fabric involved and the composition of the liquor. However, it is usually essential to have a pickup of at least 100%, generally up to 150% or so, preferably in the range of 1 l0-l 15%, to insure complete encapsulation of the fibers and optimum results. This is considerably higher than pickup used in the normal dyeing of polyester fabrics (usually 80-85% by weight of the dry fabric).

The temperature of the air circulating in the pin tenter frame may be the same throughout or the temperature may be varied, for example, decreased from 400F at the inlet to 360-370F at the outlet. Preferably the using a dwell time in the range of -90 seconds with 30-60 seconds preferred although optimum conditions for any particular situation will depend on the fabric construction and other conditions. A unique aspect of the invention is that, while in prior art procedures, predrying of dye-padded textile is carried out slowly to avoid migration, drying in the tenter frame can occur rapidly, i.e. water may be essentially flashed off without disadvantage in the first few stages or zones of the frame, particularly in the case where the temperature of the air is sequentially reduced in the frame from about 400F in the first one or two zones to 360370F for the last several zones before discharge. Such temperature variation is not, however, essential to obtain the advantages of the invention.

In a further modification of the invention, it is possible to subject the fabric to live steam during the tenter dyeing/setting/finishing is carried out at 360370F frame processing or otherwise. This may even further improve the quality of the dyeing obtained.

The invention is illustrated but not limited by the following examples:

EXAMPLE 1 A 100% polyester spunlaced nonwoven construction was padded to obtain a wet pick up of 150%. The pad liquor contained:

1.5% Levalin TPC 2.0% Palanil Brillant Blue F (Disperse Blue 87) 1.0% ammonium polyacrylate (22% solids) 5.0% of aqueous acrylic polymer emulsion containing 45% solids (/20 soft film-forming ethyl acrylic acrylate/butyl acrylate copolymer) The fabric was fed to the tenter with a 4% overfeed. The temperature of the tenter frame was set at 370F and the fabric speed was controlled to obtain a dwell time of 30 seconds. Examination of the thus processed fabric revealed a very uniform dyeing, Additionally surface distortion and pill resistance were improved.

EXAMPLE 2 A 100% spunlaced nonwoven polyester fabric was padded to obtain a wet pickup of about 1 15% using the following pad liquor:

1.5% Levalin TPC 2.0% Palanil Brilliant Blue F (Disperse Blue 87 1.0% ammonium polyacrylate (22% solids) 12% of aqueous acrylic polymer emulsion containing 45% solids (80/20 soft film-forming ethyl acrylate/butyl acrylate copolymer) 0,03% ammonium hydroxide 0.01% octyl alcohol (antifoaming agent) The fabric was fed to the tenter frame with a 25% overfeed. The temperature of the tenter frame was set at 380F and a dwell time of 45 seconds was employed. The product was uniformly dyed and demonstrated outstanding finish and stability properties.

It will be recognized that various modifications may be made in the foregoing examples without departing from the invention as defined in the following claims:

What is claimed is:

1., A process for dyeing a spunlaced nonwoven polyester fabric which comprises padding said fabric with an aqueous pad liquor including disperse polyester dye, leveling agent and ammonium polyacrylate and then passing the thus padded fabric through a tenter frame at 350 to 400F for 20 to 90 seconds whereby said fabric is continuously and simultaneously dyed and heat set said fabric being overfed to the tenter frame.

2. The process of claim 1 wherein said fabric is spunlaced nonwoven, said pad liquor includes a finishing agent and the fabric is finished and cured with the dyeing and heat setting on the tenter frame.

3. The process of claim 1 wherein the fabric is held .in the stretched condition while passing through the fed to the tenter frame in an amount less than 30%.

l 1= l =l =l 

1. A PROCESS FOR DYEING A SPUNLACED NONWOVEN POLYESTER FABRIC WHICH COMPRISES PADDING SAID FABRIC WITH AN AQUEOUS PAD LIQUOR INCLUDING DISPERSE POLYESTER DYE, LEVELING AGENT AND AMMONIUM POLYACRYLATE AND THEN PASSING THE THUS PADDED FABRIC THROUGH A TENDER FRAME AT 350* TO 400*F FOR 20 TO 90 SECOND WHEREBY SAID FABRIC IS CONTINUOUSLY AND SIMULTANEOUSLY DYED AND HEAT SET SAID FABRIC BEING OVERFED TO THE TENTER FRAME.
 2. The process of claim 1 wherein said fabric is spunlaced nonwoven, said pad liquor includes a finishing agent and the fabric is finished and cured with the dyeing and heat setting on the tenter frame.
 3. The process of claim 1 wherein the fabric is held in the stretched condition while passing through the tenter frame.
 4. The process of claim 2 wherein said fabric is 100% polyester.
 5. The process of claim 2 wherein said pad liquor includes an ethoxylated alkyl aryl sulfonate as leveling agent and a curable acrylic resin as the finishing agent.
 6. The process of claim 1 wherein said fabric is subjected to live steam while passing through the tenter frame.
 7. The process of claim 1 wherein the fabric is overfed to the tenter frame in an amount less than 30%. 